The invention relates to an endoscope having an instrument shaft having a controllable distal end piece, the position of which relative to the instrument shaft can be altered by means of at least one tension wire, which is actuable proximally of the instrument shaft and is guided through a guide tube fixed at both ends with respect to the instrument shaft.
An endoscope of the smallest practicable external diameter, may have in addition to optics and photoconductors, a probe canal, and a distal end piece which is deflectable at least to one side. The small external diameter of such endoscopes, enable diagnosis and therapy to be carried out in parts of the body and organs thereof which are difficult to access, for example, in the bile duct, in the ureter or in a blood vessel.
German patent application No. 2,402,886 discloses a flexible fibre endoscope having a deflectable distal end. Bending of said distal end is effected by means of tension wires which are actuable proximally of the endoscope. To this end, the tension wires are threaded through rings, which loosely surround the bundle of fibres of the endoscope. The rings extend in a direction parallel to the axis of the endoscope with two orientation extensions lying diametrically opposite to each other. The orientation extensions of adjacent rings slide in opposite apertures therein to provide orientation articulation. The said extensions of the rings are shaped as circular segments, with the apertures being correspondingly shaped.
German patent specification No. 2,150,595 discloses a similar endoscope having a deflectable distal end, to that disclosed in German patent application No. 2,402,886.
There is disclosed in German patent specification No 1,766,809 also, an endoscope having a deflectable distal end. The endoscope has a distal end piece formed substantially from a helically wound strip, which is surrounded by a flexible sleeve. The helically wound strip is connected at one end to the lens attachment of the endoscope, the other end of said strip being connected to a flexible tube extending in the proximal direction. Bending of the distal end piece is effected by means of tension wires secured to the lens attachment and extending in the proximal direction to a handle part of the endoscope, which has a tension wire actuating device. The tension wires are surrounded by closely helically wound wires, the ends of which are secured, on the one hand in the actuating device and on the other hand at the distal end of said flexible endoscope tube, thereby to provide what is in structure and effect a Bowden cable. There are also provided, reinforcement wires secured to the lens attachment and in the proximal direction inside the flexible bending region of the end piece, in order to counteract contraction of the bending region upon actuation of the tension wires, and in order to prevent, as far as possible, breakage of the distal end piece, which is preferably constructed so as to be very thin, being in the form of a helically wound strip as mentioned above.
The teaching of German patent application No. 2,402,886 and German patent specification No. 2,150,595 that the deflectable distal end piece should comprise elements connected together for articulation, for example,. rings, has the disadvantage that the connections needed for providing the articulation, necessitate that the bendable shaft has so large an external diameter that the endoscope cannot be used for treating said parts of the body which are difficult of access. If, however, said external diameter is kept small enough to enable said use, at the expense of reducing free the passage of the endoscope, the space therein, for example, for auxiliary instrument canals, is undesirably restricted. If, however, according to the teaching of German patent specification No. 1,776,890 the distal outer shaft consists of helically wound wire, then in order to avoid material failure upon the desired bending of the deflectable end region, additional reinforcement devices, for example, reinforcement wires, must be provided. The structure of the instrument is, therefore, undesirably complex and the free passage for auxiliary instruments or flushing and suction canals is reduced in this case also.
A distal endoscope end piece, which is deflectable by means of a Bowden cable, has the disadvantage that under the load of the tension wire, the Bowden cable rests thereon in a wave form, thereby increasing the friction between the cable and the tension wire and also shortening the endoscope shaft as a whole. Optimum bending of the distal end piece is thereby prevented.